Viser treff 1-10 av 299
Dynamics and entropy in the Zhang model of Self-Organized Criticality
(Working paper; Arbeidsnotat, 2005-09-12)
We give a detailed study of dynamical properties of the Zhang model, including evaluation of topological entropy and estimates for the Lyapunov exponents and the dimension of the attractor. In the thermodynamic limit the entropy goes to zero and the Lyapunov spectrum collapses.1
Entropy via multiplicity
(Working paper; Arbeidsnotat, 2005-09-30)
The topological entropy of piecewise affine maps is studied. It is shown that singularities may contribute to the entropy only if there is angular expansion and we bound the entropy via the expansion rates of the map. As a corollary we deduce that non-expanding conformal piecewise affine maps have zero topological entropy. We estimate the entropy of piecewise affine skew-products. Examples of ...
The Capabilities of the EISCAT Svalbard Radar for Inter-hemispheric Coordinated Studies
(Journal article; Tidsskriftartikkel; Peer reviewed, 2002)
In this article we want to present the EISCAT Svalbard Radar (ESR) in some detail, as well as some of the instruments of interest for ionospheric and magnetospheric research that are located in the vicinity of it. We particularly describe how this instrument cluster, close to the geomagnetic conjugate point of the Chinese Antarctic Zhongshan station, can contribute to inter-hemispheric coordinated ...
Geodesic Webs of Hypersurfaces
(Working paper; Arbeidsnotat, 2008-12-11)
In the present paper we study geometric structures associated with webs of hypersurfaces. We prove that with any geodesic (n + 2)-web on an n-dimensional manifold there is naturally associated a unique projective structure and, provide that one of web foliations is pointed, there is also associated a unique affine structure. The projective structure can be chosen by the claim that the leaves of all ...
Feedback Equivalence of 1-dimensional Control Systems of the 1-st Order
(Working paper; Arbeidsnotat, 2008-12-09)
The problem of local feedback equivalence for 1-dimensional control systems of the 1-st order is considered. The algebra of differential invariants and criteria for the feedback equivalence for regular control systems are found.
Utilizing ubiquitous commodity graphics hardware for scientific computing
(Master thesis; Mastergradsoppgave, 2007-10-01)
Current GPUs have many times the memory bandwidth and computing power compared to CPUs. The difference in performance is getting bigger as the evolution speed of the GPUs is higher than of the CPUs. This make it interesting to use the GPU for general purpose computing (GPGPU). I begin by looking at the architecture of the GPU, and some different techniques for programming on a GPU, including ...
Frequencies of wave packets of whistler-mode chorus inside its source region : a case study
(Journal article; Tidsskriftartikkel; Peer reviewed, 2008)
A simple criterion for the m-cyclicity of the group of rational points on an elliptic curve defined over a finite field
(Journal article; Tidsskriftartikkel; Peer reviewed, 2006-02)
We give a simple criterion for the cyclicity of the m-torsion subgroup of the group of rational points on an elliptic curve defined over a finite field of characteristic larger than 3 for m = 2, 3, 4, 6, 12.
(Journal article; Tidsskriftartikkel; Peer reviewed, 2006)
Super sensor network
(Master thesis; Mastergradsoppgave, 2008-05-15)
This dissertation studies composing a super sensor network from the combination of three functional sensor networks; A Sensor data producing network, a sensor data computing network and a sensor controlling network. The target devices are today labeled as large sensor nodes. The communication are based on an IP network using HTTP as the main protocol. Bonjour is used for service discovery, with ...